Based on a new concept, a procedure combining induced membranes and cancellous autografts allows the reconstruction of wide diaphyseal defects. In the first stage of this procedure, a cement spacer is inserted into the defect; the spacer is responsible for the formation of a pseudo-synovial membrane. In the second stage, the defect is reconstructed two months later by an autologous cancellous bone graft. The aim of this study was to evaluate the histological and biochemical characteristics of these membranes induced in rabbits. Histological studies carried out two, four, six, and eight weeks following implantation revealed a rich vascularization. Qualitative and quantitative immunochemistry showed production of growth factors (VEGF, TGFPI) and osteoinductive factors (BMP-2). Maximum BMP-2 production was obtained four weeks after the implantation, and, at this time, induced membranes favored human bone marrow stromal cell differentiation to the osteoblastic lineage. Should these results be confirmed in humans, bone reconstruction could be carried out earlier than previously thought and in better conditions than expected, the membrane playing the role of an in situ delivery system for growth and osteoinductive factors.

Graphite/LFP commercial cells are stored under 3 different conditions of temperature (30°C, 45°C, and 60°C) and SOC (30, 65, and 100%) during up to 8 months. Several non-destructive electrochemical tests are performed at different storage times in order to understand calendar aging phenomena. After storage, all the cells except those stored at 30°C exhibited capacity fade. The extent of capacity fade strongly increases with storage temperature and to a lesser extent with the state of charge. From in-depth data analysis, cyclable lithium loss was identified as the main source of capacity fade. This loss arises from side reactions taking place at the anode, e.g. solvent decomposition leading to the growth of the solid electrolyte interphase. However, the existence of reversible capacity loss also suggests the presence of side reactions occurring at the cathode, which are less prominent than those at the anode. The analyses do not show any evidence about active-material loss in the electrodes. The cells do not suffer substantial change in internal resistance. According to EIS analysis, the overall impedance increase is 70% or less.

Modelling of lithium-ion batteries calendar ageing is often based on a semi-empirical approach by using, for example the Arrhenius acceleration model. Our approach is based on Eyring acceleration model, which is not widely used for electrochemical energy storage components. Parameter identification is typically performed without taking into account the state-of-charge (SoC) drifting. However, even in rest condition, battery cells' SoC drifts because of capacity losses (self-discharge and capacity fade). In this work we have taken into account the SoC drift during calendar ageing tests. For this, we considered available capacity (Ah) instead of SoC (%) as ageing factor. Then, the analytical solution of the problem leads to the use of the Lambert W function in the model formulation. Simulation results show that Lambert-Eyring model is more accurate and allows a reduction in the number of parameters to be identified.

In this paper we present an innovative and precise way to calculate the available capacity in a battery. This quantity is essential to assess the ageing process during real use or ageing tests. Classical methods for measuring the available capacity in a battery are very dependent of impedance and relaxation state of the battery. Consequently, these methods are not suitable to quantify reversible and irreversible capacity losses occurring on batteries. We propose an indirect measure of available capacity that reduces the distortion caused by battery relaxation and impedance changes. This new method provides more accurate results allowing to distinguish reversible from irreversible part of capacity losses. The obtained results on calendar ageing tests are used in a second part to model both self-discharge and capacity fade in a global approach by using the generalized Eyring relationship.

In 1978 it was reported [1] that laser light counterpropagating in a glass optical fiber could inscribe a Bragg diffraction grating, ostensibly by altering the local refractive index of the glass in a periodic manner through an optical damage mechanism. Now, 20 years later, this discovery underscores a global multi-million-dollar activity in the manufacture of Bragg fiber gratings for the emerging photonics industry. Indeed, fiber optic gratings have asserted themselves as key elements in Mach±Zehnder interferometers for dense wavelength division multiplexing (DWDM) systems that enable fibers to carry more channels (wavelengths) of information. DWDM, in turn, has blossomed into a multi-billion-dollar optical bandwidth solution to fiber saturation created by burgeoning Internet traffic. In a broader context, Bragg gratings find widespread use in integrated optics devices such as distributed feedback lasers, filters, compensators, and mirrors for optical interconnects. Of course, this simple optical element can also find application across the entire field of spectroscopy, but the present trend toward miniaturization has created a new impetus for developing materials and methods to implement Bragg gratings in semiconductor and dielectric micro-optoelectronic benches for chemical sensing (biochips). Optical methods are among the preferred techniques for fabricating Bragg gratings. Ironically, there is as yet a rather incomplete understanding of the mechanisms used to create physical or refractive index gratings by photoinscription into glasses. [2] In this communication, we describe the preparation of acrylate-modified silica±titania sol-gel glass thin films and their use in direct optical ªself-processingº of micro-optical diffractive elements. For some time, we have been exploring the chemistry and photoprocessing of hybrid organic±inorganic sol-gel glasses for integrated optics device fabrication. [3,4] In this context, we were motivated to examine the potential of these materials for optical data storage and grating fabrication. Hybrid glass media would be particularly attractive for these purposes if a single-step photoprocess were involved. While investigating a variety of multinary hybrid glasses, we discovered that the incorporation of simple titanium alkoxide precursors yielded a particularly responsive glass for grating fabrication. We have shown previously that photoresponsive hybrid glasses can be used to record microscopic volume (refractive index) gratings in ridge waveguides by irradiation with an ArF + laser (193 nm) through a phase mask. [5] To create surface-relief gratings (SRGs) from hybrid glasses, a different procedure is required. Earlier research by our group [6] showed that volume compaction occurs during photoinduced acrylate monomer polymerization in families of hybrid glasses. Densification occurs by carbon±carbon bond formation during polymer chain growth, which induces collateral structural relaxation and condensation reactions in the metastable silica network. Since spatially resolved ...

In hybrid vehicles, lithium-ion cells constituting a battery pack are frequently used to provide and recover high power in order to assist the vehicle's Internal Combustion Engine (ICE) powertrain. This usage is more present in mild hybrid applications where the battery does not have long discharge time. In such conditions, the pack's series resistance R S proved to be an important parameter to monitor since its evolution depends on the cells characteristics (manufacturing tolerances, temperature...). This resistance, monitored by the Battery Management System (BMS), reflecting the available power level in the cell can be used as an indicator to enhance the security of the battery pack. Its evolution can be used to quantify its aging (State of Health). This paper presents an online approach to identify the cells series resistance based on a direct estimation of R S . This parameter can be usually identified through the voltage drop occurring across the cell caused by a high current variation profile (mild hybrid conditions).These estimated values are then filtered with an "exponential moving average" method to limit the measurement noise effect. This approach provides good results for mild hybrid conditions, while minimizing the computing power required.

The purpose of this paper is to analyse efficiency degradation of lithium-ion batteries. Two lithiumion cell technologies are considered under calendar ageing. It is well known that ageing mechanisms have an impact in cells' performances. Most of studies focus on capacity fade and impedance rise but efficiency is less frequently studied. However, from the application point of view, battery efficiency degradation directly impacts the system energy efficiency. Results reveal the importance of considering battery ageing in the design phase of electric vehicles, not only for capacity but also for efficiency reasons: efficiency degradation depends of the technology, so when comparing two technologies one must take into account the cells' performances not just when cells are fresh but during the whole lifespan. Another finding reported in this paper is the high correlation between capacity fade and energy efficiency for the tested technologies. Finally, two empirical models for energy efficiency degradation were developed in both technologies: the first one is based on Eyring relationships and the second one lies on the existing correlation between capacity fade and efficiency. Quality of each model is reported for both model types and battery technologies.

Efficient surface gratings are UV imprinted in an acrylate-rich hybrid solgel glass. Structural changes occurring in the material upon exposure to light are investigated. Large amplitude modulation (700 nm) and low surface roughness (0.2 nm) were measured by atomic force microscopy. Diffraction efficiencies were found to be close to theoretical predictions. The method of fabrication does not involve any etching step, and an all-UV process is proposed. The gratings are resistant to temperature and to solvent effects. These devices could have useful applications in sensor and spectroscopic devices.